DIY Floor Jack Repair Guide

If your floor jack won’t lift, feels weak, not going back, or you think there is something wrong with it, you’ve come to the right place.
In this guide, I will tell you everything you need to repair your hydraulic jack and put it back to work.

Floor Jack Won’t Lift (5 Causes & Solutions)

This problem has different degrees; there are trolley jacks or floor jacks that won’t lift the swing arm at all, even when unloaded. Others won’t lift heavy loads even when you are not trying to exceed the jack’s lifting capacity, and sometimes that jack won’t reach the full height. Besides, some floor jacks may feel weak or spongy, which affects their lifting capacity, and I’ve included them in this section.

If your hydraulic floor jack is not lifting, it is because of one of the following reasons; low hydraulic oil level, oil leak, air trap, and oil quality.

1. Low Hydraulic Oil Levels

In a few words, when you pump the handle of your bottle jack or floor jack, the plunger inside the hydraulic cylinder is pushed, compressing the hydraulic oil. As you pump the handle, you build oil pressure that pushes a piston, making the lifting arm go up.
So, when there is insufficient amount of hydraulic jack oil inside, it will not lift the weight.

Floor jacks’ hydraulic systems are sealed; that’s why low hydraulic oil levels go hand in hand with oil leaks.

How to Fix:

Start from the easiest to the more complex.
The first thing you might want to do is to top up the hydraulic jack oil.
Next, you should check for oil leaks and replace the damaged seals.

How to Fill Oil in a Floor Jack? (Watch the Video)

1. Open the release valve and fully lower the plate or bed.
2. If your jack has a cover plate, remove it.
3. Locate the oil filler hole or holes. The type of oil filler plug varies depending on the jack’s model. It could be a hex bolt, an Allen screw, or a rubber cap.
4. On models with metallic filler plugs, it’s best to loosen them a bit and stoke the handle a couple of times, allowing some oil to come out. That will relieve any pressure that may be built up inside the piston.
5. Remove the filler plug or plugs.
6. Clean any gunk or debris on the threads, preventing them from falling inside.
7. Grab a can of jack oil and a small funnel or rubber hose to pour the oil inside without spilling. Jack oils usually come in plastic bottles with a long nozzle for easy filling.
8. This step is optional. Some jacks require you to manually raise the lifting arm to the top and lock it in that position before pouring the oil.
9. Poor the oil inside the filler hole or holes. Check your jack’s user manual to check its oil capacity. Some models are more delicate than others, and if you literally top up the oil, you could damage them.
10. Take the handle down to remove any air from the system. Stop as you see that oil is coming out of the fill hole or holes without any bubbles.
11. Put the filler plugs or cap back, and you are ready.

Your jack should be fully functional again. If you noticed that your jack’s oil level was low, topped it up, and it still doesn’t work properly, it’s time to do something about the oil leaks.

2. Hydraulic Oil leaks

To deal with hydraulic oil leaks, you have to find them first. When your floor jack is leaking or bathed in oil, it is easy; the problem is when leaking area is out of your sight.

Besides visually inspecting the jack thoroughly, you can remove the plate that covers the hydraulic pump and swing the handle up and down or ask someone to do it for you as you check some key spots, such as the part of the handle that goes into the pump, the bleeder valve, filler cap, and the screws on the top of your jack.

As the jack is activated and you look for oil leaks, listen carefully and check if you hear any strange hissing noises.

Worn-out O-rings are one of the most common causes of oil leaks.

How to Fix Oil Leaks in Hydraulic Jacks?

Some leaks are easy to fix, for example:

1. Rubber filler caps fade over time, allowing oil out from the cylinder. Fixing that leak is as easy as replacing the filler cap.
2. Some filler plugs use O-rings to seal properly. If your jack has screw-type fillers and is losing oil through them, replace the plug’s O-ring.
3. The bleeder valve also has one or two O-rings. If you see oil leaking over there, carefully remove it and change them. To remove the bleeder valve, you just have to unscrew it. Be careful to do it slowly to prevent pressurized oil from coming out of the jack and making a mess.
4. The most difficult O-rings to replace are the ones where the lever gets inside the pump. To replace them, you must remove the lever, which takes some effort, but is doable and worthwhile.

If oil comes from the pump’s piston, or you don’t see any oil coming out from your floor jack, it gets trickier.
To replace the seal on the main piston or repair internal leaks, you have to remove the pump from its steel frame. It’s a job that requires some tools, a lot of time, patience, and knowledge. Besides, when opening the hydraulic pump, you will probably find damaged bearings and other mechanical parts that may be expensive and/or hard to find. So, you should consider if it’s time to ask for professional help or buy a new floor jack.

3. Air Trapped Inside

Damaged seals, leaks, wear and tear, lack of maintenance, or lifting the jack to its full capacity for long periods can let air enter the system. Air is more compressible than oil, creating bubbles that affect the jack’s performance.

💡 Solution: Bleed your Floor Jack and refill the oil.

How to Bleed a Floor Jack?

Here’s how you do it:

1. Open the release valve and lower the jack completely.
2. If your jack mechanism has a cover plate, remove it.
3. Make sure that the filler plug is tight in place.
4. Open the purge valve. If your jack doesn’t have one, rotate the handle counterclockwise until you open the valve completely.
5. With the purge valve open, pump the handle about 20 times.
6. Remove the oil filler bolt or plug carefully to release the air.
7. Put the oil filler bolt or plug back in place.
8. Secure the purge valve and check if the floor jack works properly. The lift arm should rise the same distance with every stroke. If it doesn’t repeat the same process until you are sure no air is left inside the system.

4. Worn-out Oil

Over time, oil gets contaminated, oxidates, and loses viscosity and other properties. As it fades, it loses its capacity to build up enough hydraulic pressure to make your jack work effectively. If you can’t find any oil leaks, the oil level is perfect, and you don’t remember when it was the last time you changed the oil, this may help to bring your jack back to life.

💡 Solution: Change your jack’s oil.

You can easily do this by following the instructions on how to top up your jack’s oil, just adding one more step: You have to drain the old oil. Few jacks have draining plugs; if your jack has one, you just have to remove the drain plug before filling it with new oil. If it doesn’t, you will have to remove the oil using the fill hole. To do so, you will have to tilt the jack until all the old oil comes out.

5. Wrong Hydraulic Oil

Have you recently filled the hydraulic oil in your car jack? Did you check the recommended oil specification in the user manual?

Ensure the hydraulic fluid has a viscosity of ISO 22 or ISO 32. It is okay to use a substitute oil for your hydraulic jack in an emergency situation. However, long-term use of these fluids can cause failures.

💡 Solution: Drain the oil and replace it with recommended jack oil.

Floor Jack Won’t Stay Up

Below, you will find the most common causes and solutions to why your floor jack lowers by itself, even when unloaded.

1. Air Trapped Inside

Air in the system can prevent the jack from staying up because it affects the performance and behavior of the hydraulic fluid.

💡 Solution: Bleed your Floor Jack and replace.

2. Defective Release Valve

A worn release valve can cause the jack to lower on its own.

💡 Fix: Repair or Replace the Release Valve.

If your floor jack’s bleeder valve is operated by rotating the handling, doing this may be pretty difficult. You have to remove the handlebar and the handle socket to access the release valve. In some bigger size jack models, you can access the valve without further disassembly. In others, you will have to disengage the hydraulic cylinder from the frame, which is more complicated.

If your floor jack has an independent bleeder valve, it’s much easier to access.

Before replacing the valve, check the O-ring/s; maybe it just needs new ones. If you find them ok, check for signs of damage on the bleeder valve’s surface and replace it if needed. New bleeder valves usually also bring new O-rings.

If you find a schematic or a drawing with the part lists of your jack, it is best to have it handy before starting to work on your jack.

3. Worn O-rings or Seals / Oil Leaks

Floor jacks have many O-rings and seals; some help to keep the oil inside the system, and others help to keep the pressure built when you pump the handle. When some of these O-rings or seals fail, they will fail to hold the hydraulic pressure, causing the jack’s arm to fall.

Not all the O-rings and seals that cause this problem leave visible oil leaks, but if you are experiencing this problem and your floor jack leaks oil, it’s a symptom that something may be wrong with them.

Solution: Replace the defective O-rings and Seals.

To fix this problem, you can check the item “Dealing with hydraulic oil leaks” above.

It’s important to highlight again that if the failure is in the master cylinder, it may be good to consider asking for professional help or replacing your floor jack.

Floor Jack Won’t Go Down

1. Air Trapped Inside

This can also be one of the main reasons why a floor jack won’t go down. Air may change the pressure inside the cylinder preventing the release valve from releasing the hydraulic fluid properly. Besides, air bubbles can cause an uneven distribution of pressure which can jam the system, preventing the lift arm from moving.

Solution: Bleed your Floor Jack.

If the jack is lifting a vehicle, use another floor jack to help you remove the stuck jack before bleeding it. Then follow the procedure described above to bleed your floor jack.

2. Release Valve Problems

Problems with the release valves or the linkage between them and the handlebar can prevent a floor jack from going down.

How to Fix:

• Handlebar linkage problems
  If the release valve on your floor jack is operated by the handlebar, check that it’s effectively turning the valve as you turn the handlebar.

Sometimes, the linkage that connects the handlebar with the release valve fails or breaks. You can remove the handlebar and open the release valve using pliers or an adjustable wrench. Once you have released the floor jack from the vehicle, then you can take a deeper look and fix the problem.

Some handlebars are just like a hex socket that twists the release valve without any other type of mechanism in between. These handlebars are usually made from weak materials and get rounded over time, failing to bite the release valve properly. In that case, you will have to replace the handlebar or consider if it’s worth welding a cheap socket on the tip of the handlebar to keep your floor jack operational. There isn’t much you can do about this case.

• Blocked release valve
  Release valves can stick or block due to old or inadequate oil. You can remove the release valve as explained above and clean it or replace it.

3. Stuck or Damaged Mechanical System

Stuck pistons, misalignment between the trolley and the swingarm, and other mechanical problems can block the jack’s lifting mechanism.

How to fix:

Don’t try to fix the floor jack while it’s holding a vehicle. Use another floor jack first to release the stuck floor jack from the vehicle before checking it up.

Then inspect the mechanical parts and check that all the moving components are properly aligned. Also, check for loose parts of the swingarm that may be jamming it up.

Another thing that can be helpful is lubricating the moving parts, such as the piston, the linkage mechanism, and the release valve. Use a good penetrating oil such as WD-40 to remove rust and grime blocking the mechanism.